This proposal is for renewal of the Johns Hopkins Drug Abuse Research Center. Laboratories involved are those of S.H. Snyder, M.J. Kuhar, J.T. Coyle and E. Richelson. Numerous independent and collaborative projects focus on mechanisms relating to the actions of opiate drugs as well as central stimulants in adult and developing organisms. Studies will utilize biochemical and autoradiographic investigations with intact brain tissue as well as brain aggregation cultures.